View Full Version : Changing Preamp tubes in a DR Clone for More headroom, nicer breakup
jacksonburn
05-06-2010, 02:53 PM
I got one of the Weber clone Deluxe Reverbs and would like to get more headroom before breakup and a smoother sounding breakup. It's kinda harsh now. Really like the cleans though. What preamp tubes and brands would you recommend for this and in what slots? Thanks!
Here's a link to the layout:
https://taweber.powweb.com/store/6a20_layout.jpg
wyatt
05-06-2010, 04:05 PM
Well, you can certainly smooth it out with tube rolling, but you aren't going to get any substantial boost in headroom from changing preamp tubes.
There are a few things to look at:
1.) The DR uses lower B+ voltage than the larger BF/SF Fender combos, which impacts preamp headroom
You can change this by changing the to 10K dropping resistors to the SR/TR values (4.7K and 1K). Increase B+ in the preamp and PI, more preamp headroom for the more shimmering SR/TR style tones. You trade off a little touch sensitivity though.
2.) The midrange. A DR is voiced like larger BF/SF combos that have their mid knobs dimed. You could revoice the amp but,...why.
3.) The power amp. Between this and the speaker (below), this is where you have to go. People alwasy say they want a little more headroom.. This is always bull***t. A little goes no where in volume. They want (maybe need ) a noticeable boost in headroom at stage volumes and with the power amp that means at least doubling the RMS wattage (increasing output by about 3db). If the Weber can handle 6L6GC's they would be an option, especially if you use a SS rectifier to boost B+ voltages (not, this boosts the preamp voltages as well), so you may not need the change in dropping resistors above. But this change alone isn't doubling output.
4.) The easiest way to in crease headroom in an amp is a more efficient speaker. That 3db boost you would get from completely rebuilding the power amp? Well, that can be gained by a simple speaker swap. Depending on what you are using already, you could boost 3db, or 6db or more with a new speaker. If you using an inefficient speaker, a boost of 9db or more is possible, that would be equivalent to your amp drving your current speaker with 66 watts instead of 22 watts.
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